Catheter-type instrument



March 1948. H. KRIPPEQNDORF 2,437,542

CATHETER-TYPE INSTRUMENT Filed May 5, 1944 GREATER FLEXIBILITY IMPREGNATED DMPREGNATED THREADS MORE I THREADS MORE WITH MED\UM #1 WITH MEDIUM #2 LOOSELY NTERTWINED CLOSELY INTERTWINED INVENTOR Louzb'liKz'z b oendwf B ,lwkm a ATTORNE 3 Patented Mal. 9,

ky e-14 u at CATHETER-TYPE INSTRUMENT Louis H. Krippendorf, White Plains, N. Y., as-

signor to American Catheter Corporation, Port Chester, N. Y., a corporation 01' New York Application May 5, 1944, Serial No. 534,207

2 Claims. 1

My present invention relates generally to surgical instruments and has particular reference to catheter-type instruments.

By the term catheter-type instruments, as used herein and in the appended claims, I intend to refer to the well-known kind of device which is inserted endwise into and through constricted body channels for diagnostic, therapeutic and allied purposes. Illustrative of such instruments are ureteral and urethral catheters, bougies, filiforms, and the like.

A conventional instrument of this type is of elongated character and has a uniform over-all flexibility coupled with sufficient rigidity to permit its endwise advancement. This paradoxical requirement for both flexibility and rigidity has heretofore presented a peculiar problem to the manufacturer. For example, in the case of a ureteral catheter, it must be of suflicient flexibility to permit the tip of the instrument to advance harmlessly through the constricted ureteral canal and readily to follow the curvatures encountered, yet as the flexibility is increased by the manufacturer to meet this requirement, the body portion loses some of the rigidity necessary to enable the operator to eflect the desired advancement by endwise pressure exerted upon the rear end of the instrument. Similarly, in the case of bougies or the like, it may under certain circumstances be desirable to increase the rigidity of the tip portion, yet the instrument as a whole may thereby become too inflexible to follow an irregularly curved path with adequate ease.

The principal object of my present invention is directed toward a solution of this problem, and my invention is predicated upon the discovery that a catheter-type instrument may be caused to embody diflerent flexibilities along its longi tudinal axis without materially altering its basic structural nature or impairing the other inherent qualities which it necessarily must possess. This desirable and advantageous result is achieved in an entirely practical and commercially-feasible manner,

In accordance with one conventional manufacturing procedure, the construction or a cathetertype instrument involves the formation of an initially limp fabric base or intertwined threads, this base being usually first impregnated with a flexible stiii'ening medium and then coated with a flexible varnish. In the practice of my present invention, this general procedure is adhered to,

'yet the body portion of the resultant instrument may be caused to embody a flexibility in the forward or other section thereof which is to a pre- 2 determined extent appreciably greater or less than the flexibility in an adjacent section.

This new result, and its corresponding advantages, may be accomplished in several ways, as illustratively exemplified in the following description and in the accompanying drawings in which:

Figure 1 is a perspective view of a typical catheter-type instrument illustrating the features of my present invention;

Figure 2 is an enlarged fragmentary view of a portion of the instrument with the outer coating broken away to reveal the fabric base, illustrating the preferred structure;

Figure 3 is a view similar to Figure 2 illustrating a modification;

Figure 4 is a view similar to Figure 2 illustrating a further modification; and

Figure 5 is a diagrammatic view illustrating the comparative characteristics, so far as flexibility is concerned, of a conventional cathetertype instrument and one which has been constructed in accordance with the present invention.

The features of my present invention may best be described by brief preliminary reference to convention-a1 practice.

A fabric base is first created. Usually, this base assumes the form of an elongated hollow tube, but under certain circumstances it need not have a longitudinal passageway extending through it. is formed of wined threads or slrk, c o ttp r or g nthetic flbra d the threads are braided into the desired relationship. Any weaving or other procedure may be resorted to, however, if desired, although braiding machines have proven to be admirably suited to produce a tubular or elongated fabric base or the character required. This base is initially limp in character, and is customarly impregnated with a flexible stifiening medium of suitable composition. Where the base is a tube, the imp egnation is carried out while the tube is mounted upon a suitable rod or mandrel. After wiping of! any excess, the mandrel (ii! one has been used) is removed and the imp ng medium is causedtohardenorpurefe'ither by air drying, orby subjection to a baking procedure or the like. The reinforced and strengthened fabric base is then subjected to a. series of operations during which a flexible tough varnish coating is applied to it, layer by layer, the successive coatings being cured by baking or analogous procedures. After the desired coating has been formed, it is burnished and the instrument is subjected to such other finishing processes as may be deemed desirable.

The forward tip of the instrument may be formed either prior to or after the initial impregnation of the fabric base, depending upon the nature of the instrument, and the kind and shape of tip which it is intended to have. In the case of catheters, the several openings or eyes which characterize these instruments may be formed at or near the forward tip either during the braiding of the base or during a subsequent stage of treatment.

Depending upon the nature and size of the threads originally employed in forming the fabric base, upon the dimensions of this base and upon the impregnating and coating media which are employed, the resultant instrument will have a size and flexibility of predetermined character. Heretofore, in an instrument in which the body portion is of substantially uniform diameter, the bendability and over-all semi-rigidity has been uniform throughout, being usually determined by a suitable compromise between the flexibility required for any given purpose and the stiffness called for by the Well-known method in which the instrument is to be employed.

In accordance with my invention, the essential nature of the manufacturing process remains unchanged, yet varying degrees of flexibility may be imparted to the resultant instrument along its longitudinal axis. This result may be achieved in various ways, and for illustrative purposes, I have chosen to describe and illustrate the manner in which a catheter may be caused to have an appreciably increased flexibility in its forward region adjacent to the tip, as compared with the flexibility and rigidity of the remaining main portion thereof.

Thus, in Figure 1, I have illustrated a catheter ID in which the region forwardly of the dot-anddash line A has been caused to embody a greater flexibility than the remaining main portion of the catheter.

The Preferred procedure is illustrated in Figure 2 in which I have illustrated the structure, on an exaggereated scale, in the vicinity of the dotand-dash line A. It involves a slight modification in the process of impregnating the fabric base tube II with a flexible stiffening medium.

Instead of impregnating the entire tube in one step, I first impregnate one selected section thereof, permitting or causing the medium to be cured, after which another selected section is similarly impregnated, the tw impre ating media being of suitably ehos'zenldtifiejenfigr ziposi- .other customary ingredients. There are numerous resins which can be employed, and among them are, for example, resins of the phenolic type. The was; used may be any of the usual ones, such as casto dibutyl phthalate, tri-cresyl-phospha I e.

In-ac actice, assuming that the fabric tube is to be employed in the manufacture of the catheter l0 shown in Figure 1 in which the forward region is to embody greater flexibility than the remainder, the tube may be mounted on a suitable rod or mandrel (not shown) either before or after the forward tip is formed, and may then be dipped vertically into the first impregnating medium, up to the approximate line A where the greater flexibility is to stop. The excess is then wiped off and the partially impregnated tube may be placed in a suitable oven to bring about 9. ouring of the impregnating medium. The entire tube may then be immersed bodily into a bath of the second impregnating medium whereby the balance of the tube becomes impregnated, and after wiping off any excess from the outside surface, the rod .or mandrel is withdrawn and the tube is placed in a suitable oven to bring about the desired curing. Subsequently, the tube is handled in the usual fashion to form on it the outer coating 12 of flexible varnish, which may be composed, for example, of a tung oil base, a Phenolic resin, and a suitable plasticlzer.

In preparing the two impregnating media referred to in the preceding Daragraph -the one which is to have the greater flexibility will contain more. of the plasticizingingredient, while the otherdne-wiir'c'oritain relatively less plasticizer.

One of the advantages of this procedure lies in the fact that the initial partial dipping-of the tube is accompanied by a capillary action which introduces the first impregnating medium in gradually-diminishing amounts into the region rearwardly of the line A, whereby the finished product is devoid of any undesirable clean-cut line of demarkation between the region of greater flexibility and the remaining portion of the instrument.

In Figure 3 I have illustrated another means whereby the desired effect may be achieved. In this case, the fabric base tube I3 is so braided or otherwise formed that the threads in the region rearwardly of the line A1 are more closely intertwined than in the region forwardly of this line whereby the flexibility of one region is different from the other. Where the tube is formed by means of a braiding machine, this result can be brought about by adjustments of the braiding machine during the course of its operation.

The base thus formed need not necessarily be subjected to two successive preliminary impregnations, and the ordinary manufacturing procedure may be followed to impregnate the base with a flexible stiffening medium, and ultimately to form on it the outer coating 14 of flexible varnish. 'I'he stiffening medium and the varnish may each be of the same general composition hereinbefore referred to. It will be understood, however, that the two-stage impregnation described in connection with Figure 2 may be combined, if desired, with the modification of the base tube itself as illustrated and described in connection with Figure 3.

In Figure 4. I have illustrated another illustrative procedure in which the base tube is formed of two separate portions l5 and I5 arranged in overlapping nested relationship. These portions may be formed of different materials or may be composed of threads of the same material but having different calibres. Or, if desired, both the material of the threads, and their calibres may be different. In any case, the portion I5 is caused to embody an inherent structure which is suitably diflerent from the portion It so that after impregnation and curing, these two portions will exhibit appreciably different flexibilities.

In the creation of an instrument as shown in Figure 4, the overlapping of the portions l5 and I6 is brought about in the region of the line A2 in such a manner that the forward section of the resultant instrument will be of appreciably greater flexibility than the r maining portion.

In practice, the separate portions of the base tube may be brought into the overlapping relationship shown during the course of the braiding procedure, This composite base tube may then be subjected to the usual steps of impregnation and coating to form the flexible varnish coating 11 (which may be of the same general composition hereinbefore referred to), and in the finished instrument it will be found that the exterior surface of this coating is entirely smooth and uniform despite the overlap in the interior, which is shown on an exaggerated scale in Figure 4.

Obviously, if desired, one or the other of the portions 15 and I6 may be more loosely or more closely intertwined, to enhance the differences in flexibility which are to be achieved; and the procedure described in connection with Figure 2 may be combined with this overlapping base tube structure if the results to be achieved justify a two-stage impregnation.

Another way of accomplishing the desired result lies in curing the varnish coating to a greater extent in one section than in another. For example', in producing a catheter having the characteristics shown in Figure 1, the normal and conventional procedure may be followed throughout, and the rearward part of the instrument may then be subjected to an additional baking or curing whereby a greater rigidity is imparted to it. In practice, this may be accomplished by dipping the forward region in a suitable oil or other liquid while the entire instrument is subjected to a baking temperature.

Usually, the coating is of resinous character, adequate to produce a tough flexible film having a smooth glossy surface and resistant to water, body fluids generally, and standard types of sterilization.

The basic diiference between the instrument of Figure 1 and the ordinary type of instrument is indicated diagrammatically in Figure 5. If the ordinary catheter I8 is pressed endwise against an abutment wall l9, by pressure exerted in the direction indicated by the arrow 20, it will buckle throughout its length. On the other hand, if the instrument In of Figure 1 is similarly pressed against an abutment l9 by a similar pressure exerted along the direction of the arrow 2|, it will buckle in the forward region of greater flexibility, but not otherwise. Accordingly. when the instrument I0 is inserted into and advanced through one of the ureters or through any other similar constricted body canal, it will feel its way more easily past the curvatures encountered, and this makes the operation safer and simpler.

While I have illustrated a catheter, it will be understood that the invention is equally applicable to any catheter-type instrument, whether,

hollow or not; and while I have chosen to illustrate the manner in which the forward region of the instrument may be made more flexible than the balance, it will be understood that other relative flexibilities may be produced, depending upon particular requirements.

In general it will be understood that the details herein described and illustrated to explain the general nature and objective of the invention may readily be modified by those skilled in the art without departing from the spirit and scope of the invention as expressed in the appended claims.

Having thus described my invention and illustrated its use, what I claim as new and desire to secure by Letters Patent is:

1. In an elongated flexible catheter-type instrument, an initially limp fabric base impregnated with a flexible stiffening medium, said medium in one region of said base being of appreciably greater flexibility than in a longitudinally-adjacent region thereof, the flexibilities of the corresponding sections of the instrument being correspondingly afiected.

2. In an elongated flexible catheter-type instrument, an initially limp fabric base impregnated with a flexible stiffening medium, said medium in the forward region of said base being of appreciably greater flexibility than in the adjacent rearward region, the flexibilities of the corresponding sections of the instrument being correspondingly affected.

LOUIS H. ICRIPPENDORF.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 204,905 Lockwood June 18, 1878 309,177 Lee Sept. 25, 1888 1,776,879 Baekeland Sept. 30, 1930 2,237,218 Flynn Apr. 1, 1941 FOREIGN PATENTS Number Country Date 8,249 Great Britain July 7, 1885 372,096 France Mar. 23, 1907 476,004 France July 7, 1915 163,694 Switzerland Nov. 1, 1933 

